1. The gorge n________ to 350 feet as the river rushes through the two-mile-high mountain.
2. on a distant mountain was a sign in 20-foot ___________(汉字).
3. They are just beginning to e_________ the country’s natural resources.
4. We sailed into the c_________ site of the dam.
5. And everywhere he goes, he sends himself a _____________(明信片).
